銀離子於酸性環境中對斑馬魚胚胎發育及離子調控之危害

Silver exposure impairs the development and ion regulation of zebrafish embryos in an acidic environment

孔耕心(Kung Geng-Xin)

指導教授 ： 林豊益

國立臺灣師範大學/理學院/生命科學系/碩士(2021年)

https://doi.org/10.6345/NTNU202101032

摘要

奈米銀在近年來被廣泛地運用於醫療及化妝品產業，其廢棄材料表面釋放出的銀離子會危害水生生物。然而，目前對於銀離子在不同酸鹼值環境中的毒性差異並不瞭解。本研究利用斑馬魚胚胎為水生生物模式，將其暴露於含有0、0.1及0.25 ppm AgNO3之pH 5或pH 7環境中，以評估銀離子毒性的差異。在暴露96小時的結果中可以得知銀離子的胚胎發育影響程度隨著濃度升高而增加。在銀離子的暴露後胚胎體長顯著下降，而卵黃囊面積則會增加。銀離子亦導致胚胎耳石囊面積及耳石面積下降，影響胚胎的內耳系統。另外，側線神經丘及毛細胞數目下降也反映出銀離子對胚胎側線的影響。值得注意的是：酸環境(pH 5)中會增加銀離子在體長、卵黃囊、耳石囊以及耳石上的影響。另一方面，銀離子降低離子細胞開口面積及數目，阻礙胚胎的離子調節功能，並且導致NaRC及HRC數目顯著降低，增加胚胎適應酸環境的困難性。另外，30分鐘及2小時的實驗中可發現：銀離子會藉由增加離子細胞的氧化壓力程度，進而誘發細胞凋亡機制。總結以上結果，本研究認為酸環境會增加銀離子對魚類的危害。

關鍵字

銀離子 ； 酸環境 ； 斑馬魚 ； 離子細胞 ； 氧化壓力

並列摘要

Silver nanoparticles are widely used in medical treatments and cosmetic industries. Ag+ released from the particles causes physiological damages to aquatic organisms. However, it is still unclear how environmental pH influences the toxicity of Ag+. In this study, zebrafish embryos were incubated in pH 5 or pH 7 water containing different concentrations of AgNO3 (0, 0.1 and, 0.25ppm) to examine the toxic effect of Ag+. After 96 h exposure, Ag+ influenced embryonic development in a dose-dependent manner. The body length, otic vesicle size, and saccular otolith size were significantly decreased, yet the yolk sac size was increased. Moreover, the neuromast and L1 hair cell numbers were reduced by Ag+. Acidic water (pH 5) enhanced the toxic effects of Ag+ on body length, size of yolk sac, otic vesicle, and saccular otolith. Ag+ also impaired ion regulation of embryos by reducing the apical opening size and cell number of ionocytes. The cell numbers of both NaRC and HRC were significantly decreased by Ag+. After shorter exposures (30 min and 2 h), Ag+ increased the oxidative stress of ionocytes and induced cell apoptosis. In conclusion, this study suggests that acidified environments might intensify the Ag+ toxicity to fish.

並列關鍵字

Silver ions ； Acidic freshwater ； Zebrafish ； Ionocyte ； Oxidative stress

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